Delayed gelling agents

a gelling agent and delay technology, applied in fluid removal, chemistry apparatus and processes, borehole/well accessories, etc., can solve the problems of limited method in practice, limited wet recovery, and unswept oil left behind, and achieve high brine tolerance

Active Publication Date: 2012-02-16
UNIVERSITY OF KANSAS +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0038]Chromium and zirconium are the preferred multivalent cations in high salinity brines including hard brine. High salinity brine contains on the order of at least about 30,000 ppm total dissolved solids. Thus, the combination of the particular chelating or sequestering agent in conjunction with the preferred chromium(III) and Zr(IV) cations confers high brine tolerance.

Problems solved by technology

However, sweep recovery is limited by the so-called “thief zones,” whereby water preferentially travels through the more permeable regions or fractured zones of the reservoirs, bypassing the less permeable zones and leaving unswept oil behind.
However, the method is limited in practice because subsequent water injections always remove some of the polymer.
Hence the polymer becomes washed out and again presents the problem of allowing the injection fluid to avoid the less permeable zones.
However, these patent applications address gelation, and not gelation rate.
Thus, one additional problem is that gelation can occur too quickly, thus preventing the polymer from even reaching the deepest zones before it gels.
The delay occurs because of the time required for the complex to dissociate, thus releasing the cations for the gelation reactions to occur.
While the complexed multivalent metal crosslinkers described above produce gels at much slower rates than Cr(III) chloride, the rate of gelation is still much too fast for placement of gelant deep into the oil-bearing formations.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

NA-AMPS Cage Containing PEI / Chromium

[0053]A representative multivalent cations and cationic polymer-loaded crosslinked polymeric particle or cage, herein referred to as “d12” was prepared using an inverse-emulsion polymerization.

[0054]In such process, an aqueous mixture containing 22 g of 50% sodium 2-acrylamido-2-methylpropane sulfonate (sodium AMPS), 10 g of 50% PEI (2000 Mw), 6.5 g distilled water, 35 mg poly(ethylene glycol) (258) diacrylate, 1.61 g Chromium (III) acetate hydroxide (CH3COO)7Cr3(OH)2 as the dispersed phase (6400 ppm Cr+++) and an oil mixture of 20 g kerosene, 3.2 g Span 83 and 1.8 g polyoxyethylene sorbitol hexaoleate (PSH) as continuous phase were prepared.

[0055]The inverse-emulsion was prepared by mixing the aqueous phase and the oil phase, followed by rapid homogenization using a homogenizer. After adding the emulsion and 20 mg VAZO® 52 as an initiator into a 250 ml flask and purging this mixture with nitrogen for 15 minutes, polymerization was carried out in ...

example 2

NA-Vinyl Sulfonate Cages Containing PEI / Chromium

[0056]In this example, we replaced sodium AMPS with sodium vinyl sulfonate (sodium VS) as a monomer in the synthesis of Example 1 above.

[0057]A representative multivalent cations and cationic polymer-loaded crosslinked polymeric particle, here forth referred to as “d12S” was prepared containing 6400 ppm Cr(III) using inverse-emulsion polymerization. In such process, an aqueous mixture containing 30 g of 25% sodium VS, 8 g of 50% PEI (2000 Mw), 34 mg poly(ethylene glycol) (258) diacrylate, 1.60 g chromium (III) acetate hydroxide (CH3COO)7Cr3(OH)2 as the dispersed phase and an oil mixture of 20 g kerosene, 3.2 g Span 83 and 1.8 g PSH as continuous phase were prepared.

[0058]The inverse-emulsion was prepared by mixing the aqueous phase and the oil phase, followed by rapid homogenization using a homogenizer. After adding the emulsion and 20 mg VAZO® 52 as an initiator into a 250 ml flask and purging this mixture with nitrogen for 15 minutes...

example 3

NA-AMPS Cage Containing PEI

[0059]A representative cationic polymer-loaded crosslinked polymeric particle or cage, herein referred to as “d12-[no Cr]” was prepared using an inverse-emulsion polymerization.

[0060]In such process, an aqueous mixture containing 22 g of 50% sodium 2-acrylamido-2-methylpropane sulfonate (sodium AMPS), 10 g of 50% polyethyleneimine (2000 Mw), 8.1 g distilled water, 35 mg poly(ethylene glycol) (258) diacrylate as the dispersed phase and an oil mixture of 20 g kerosene, 3.2 g Span 83 and 1.8 g polyoxyethylene sorbitol hexaoleate (PSH) as continuous phase were prepared.

[0061]The inverse-emulsion was prepared by mixing the aqueous phase and the oil phase, followed by rapid homogenization using a homogenizer. After adding the emulsion and 20 mg VAZO® 52 as an initiator into a 250 ml flask and purging this mixture with nitrogen for 15 minutes, polymerization was carried out in 50° C. oil bath for 7 hours. VAZO® 52 is a low-temperature polymerization initiator, wh...

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Abstract

The invention is directed to delayed gelation agents comprising a degradable polymeric cage containing therein one or more gelation agents. The cage degrades in situ, e.g, in an oil reservoir, thus releasing the gelation agent(s), which can then crosslink second polymers in situ to form a gel.

Description

PRIOR RELATED APPLICATIONS[0001]This application claims priority to U.S. Ser. No. 61 / 372,747, filed Aug. 11, 2010 and incorporated by reference in its entirety.FEDERALLY SPONSORED RESEARCH STATEMENT[0002]Not applicable.REFERENCE TO MICROFICHE APPENDIX[0003]Not applicable.FIELD OF THE INVENTION[0004]This invention relates to compositions and processes for oil field applications. More specifically, this invention relates to degradable polymeric particles or “cages” that contain gelation agents. The cages degrade, or at least partially degrade, on exposure to higher temperatures or changes in pH, thus releasing the gelation agents. The resulting released gelation agents can then crosslink a second polymer to produce gels. In this process, the time required to degrade the particles and release the gelation agents adds significantly to the gelation time. This additional delay in crosslinking could be useful in placing the degradable polymer and further polymer package deep into target zo...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): E21B43/22C09K8/588
CPCC09K8/88C09K8/887E21B33/138C09K8/588C09K8/92
Inventor GUAN, HUILIBERKLAND, CORYMORADI-ARAGHI, AHMADLIANG, JENN-TAIZORNES, DAVID R.NEEDHAM, RILEY B.CHENG, MINHEDGES, JAMES H.JOHNSON, JAMES P.SCULLY, FAYE L.
Owner UNIVERSITY OF KANSAS
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